The universally programmable quantum gate array is not possible. The universality of a programmable gate array means that the gate array has an ability to treat an arbitrary program. The program in making such a gate in quantum computer is that there are not enough places to store a continuous valued information of an arbitrary unitary operation. But, there is a practical way. We store the continuos vlued information into the probability amplitude of a quantum state. Therefor, the state is programmed. Then, the practicllly programmable quantum gate array retrieve the information from the programmed state into a prepared data register to operate an unitary operator corresponding to the programmed inforamtion. This is probabilistically achievable.
The purpose of our study is to demonstrate the programmable gate array by 3-bit nuclear magnetic resonance quantum computer. We chose $J_{ij}(\theta)$ operator as an arbitrary unitary operator. $^{13}C$ -alanine molecules are used in this study.
